These are simply skills any excelent athelete will develop. I bet michael jordan can do a lot of ki feats from simply playing years of basketball. The fact you can do something they can't is not really evidence. It simply shows they have not learned it yet.

This leads of course to the question of how important the skill is to learn. As you said, using a internal strenght skill and using it to fight are two different things. So the question would be if learning the skill, but being unable to employ it at will in a conflict is really all that useful outside of party tricks. I can do a lot of neat things if I set them up properly. I can sit and not be pushed over, I can hold back multiple people on one leg with one arm. I can hold 2 fingers in a ring shape while 2 or more people pull on my fingers trying to pry them appart. I dont concider any of these things internal strength.

Actually I think Don brings up a good point with this stuff since I think a lot of the "tricks" associated with being "Ki" demos are extremely fundamental.
And Don's right, I think they have everything to do with phsyology and physics (though I disagree with the positioning bit )
Not to say they don't have value, but like Don basically says, a lot of people can pick up bits and pieces of these basic skills through years of sports training.
I think though, since those are the fundamentals, the real trick will be to speed up this process to where people can access the so called "advanced" material and make these parlor tricks more than simply body skill that is an accessory to what they do.

Don I know where you're coming from I think, and while people can access bits and parts of these skills, there's no one in the sports area that's trying to gather it together as a whole and make a more "efficient" curriculum for human movement.